The proposed research is an investigation of dynamic aspects of interactions of hormones and growth factors with normal and neoplastic cells. The major purpose of the work is to understand the mechanisms of processes which can affect cell growth, differentiation, adhesiveness, and other phenotypic differences between normal and transformed cells. We will examine binding, cellular localization and fate of fluorescent analogues of hormones and autoantibodies against insulin receptor. We will emphasize measurement of receptor motion, aggregation and interaction with intracellular and extracellular structures. In all our studies we use two new biophysical methods for measuring the mobility and distribution of cell surface components. We localize the fluorescent hormones on the cells with a highly sensitive video identification Microscopy system. A second method, denoted fluorescence photobleaching recovery gives quantitative informatin about the motion, immobilization and number of receptors on the cell membrane. In addition we use conventional biochemical and chemical methods and new methods for labeling peptide hormones. The major aims of the project include: (1) To study the relationship between hormone receptor motion, aggregation, membrane potential and the physiological response to the hormone; (2) To characterize the fate of the receptor-bound hormone, especially the relationship between internalization and degradation of the hormone and cellular response; (3) To study the relationship between internalization and capping of hormone-receptor complexes and the "down" regulation of exposed receptors; (4) To determine, with our large repertoire of fluorescent hormone analogues, whether there is a general mechanism whereby hormones first bind to specific receptors on the cell surface, are then collected at specific regions on the cell membrane, and finally are endocytosed; (5) To extend our biophysical methods. This will include the incorporation of fluorescence photobleaching recovery and video intensification microscopy into a single method and the development of a new system for quantitative substraction of nonspecific cellular fluorescence and enhancement of specific fluorescence.